Test and Fault Analysis for High Power High Frequency HV Transformer

Abstract: In order to analyze the causes for a high power high frequency HV transformer faults, a test platform is established; no-load test and wave recording are conducted for a faulty transformer and a faultless transformer. Features of test waveforms are summarized via current waveform comparison method. Based on the structure of power transformer, an equivalent circuit of the transformer considering stray parameters is put forward and a simplified circuit is come up with. The test result shows that it is distribution capacitance rather than air gap abnormity that causes high no-load current. Through the comparison of current waveforms, we can draw a conclusion that the fault is caused by the insulation breakdown of high voltage line package (layers or turns), which accords with the results through observation after the dismantlement of power transformer.  

Key words:  high power, high frequency, insulation, power transformer, test, fault analysis    

Introduction

There have been a large amount of research achievements and practical methods with regard to fault diagnosis of power frequency transformer. As the high power HV DC power source is widely used, research on the protection and fault diagnosis of high power HV high frequency transformer needs to be further advanced. The effect of stray parameters complicates its equivalent circuit and generates many new problems (such as several resonant points). Hence, some methods of diagnosing the faults of common power transformer are not suitable for high frequency HV transformer, and even lead to incorrect conclusions. In this paper, no-load test and wave recording are conducted for a faulty transformer and a faultless transformer. The analysis results are much similar to the results through observation after the dismantlement of power transformer.